Voltage-nonlinear resistors

ABSTRACT

The invention relates to voltage-nonlinear resistors having nonohmic resistance due to the bulk thereof, and more particularly to varistors which are suitable for use as elements of lightning arresters, comprising zinc oxide, bismuth oxide, antimony oxide and nickel fluoride.

United states P Mat suoka et al;

ate nt 1 1' VOLTAGE-NONLINEAR RESISTORS Inventors:

Assignee:

I Filed:

Michio Matsuoka; Yoshikazu Kobayashi; Gen Itakura; Takeshi Masuyama, allof Osaka, Japan Ltd., Osaka, Japan Sept. 19, 1973 Appl. No.: 398,779

Foreign Application'l riority Data Matsu shita Electric Industrial (10.,

ag L44 43441 -43 43 1 14 1 May 14, 1974 51 1m. (:1. ..n01 7/10 [58]Field of Search 338/20, 21; 25.2/518 [56] References Cited UNITED STATESPATENTS I 3,658,725 4/1972 Masuyama et al 252/5l8 3,687,871 8/1972Masuyama et al 252/5l8 Primary Examiner-C. L. Albritton Attorney, Agent,or Firm Wender0th, Lind & Ponack.

[5 7'] ABSTRACT The invention. relates to voltage-nonlinear resistorshaving non-ohmic resistance due to the bulk thereof, and moreparticularly tovaristors which are suitable for use as elements oflightning arresters, comprising zinc oxide, bismuth oxide, antimonyoxide andnickel fluoride.

6 Claims, 3 Drawing Figures Masuyama et al 338/20 PATENTEBHAY 14 mVOLTAGE-NONLINEAR RESISTORS Various voltage-nonlinear resistors such assilicon carbide varistors, selenium rectifiers and germanium or siliconp-n junction diodes have been widely used for stabilization of voltageof electrical circuits or suppression of abnormally high surge inducedin electrical circuits. The electrical characteristics of such anonlinear resistor are expressed by the relation:

I (V/C)" v 1. where V is the voltage across the resistor,,l isthecurrent flowingthrough the resistor, C is a constant corresponding tothe voltage at a given current and exponent n isa numerical valuegreater than 1. The .value of n is calculated by. the followingequation:

g1o( 2/ 1)l/[ g1o( a J] 2. where V and V are the voltages at givencurrents I, and 1 respectively. The desired value of C depends upon thekind of application to which the resistor is to be put. It is ordinarilydesirable that the value of n be as large as possible since thisexponent determines the extent to which the resistors depart from ohmiccharacteristics. Conveniently the, ri-value defined by I I V and V, asshown in equation (2) is expressed by m for distinguishing it from then-value calculated by other currentsor voltages.

Nonlinear resistors comprising sintered bodies of zinc oxide with. orwithout additives and non-ohmic electrode appliedthereto, have alreadybeen disclosed as seen in us. Pat. Nos. 3,496,512, 3,570,002 and3,503,029. The nonlinearity of such varistors is attributed to theinterface between thesintered body of zinc oxide with or withoutadditives and the silver paint electrode and is controlled mainly bychanging the compositions of said sintered body and silver paintelectrode."l"-herefore, it is not easy to control the C- value over awide rangeafter the sintered body is prepared. Similarly, in varistorscomprising germanium or silicon p-n junctiondiodes, it is difficult tocontrol the C-value over a wide range because the nonlinearity of thesevaristors is not attributed to the bulk but to the p-n junction. Inaddition, it is almost impossible for the varistors and germanium orsilicon diode varistors to obtain the combination of C-value higher than100 volts, n-value higher than and high surge resistance tolerable for asurge of more than 100A.

On the other hand, thesilicon carbide. varistors have nonlinearity dueto the contact between the individual grains of silicon carbide bondedtogether by a ceramic binding material, i.e. to the bulk, and theC-value is controlled by changing dimensionin the direction in which thecurrent flows through the varistors. In addition, the silicon carbidevaristors have high surge resistancewhich is suitable for'characteristicelements of lightning arresters. The characteristic elements are usedusually by connecting in series with discharging gaps and determine thelevel of the discharging voltage and the follow current. The siliconcarbide varistors, however, have a relatively low n-value ranging from 3to 7 which results in poor suppression of lightning surge or increase inthe follow current. Another defect of the arrester including thedischarging. gaps as its components is not to respond instantaneously tosurge voltage having very short rise time, suchas below I gs ltlsdesirablefor the arrester to suppress the lightning surge and the followcurrent to as low a level as possible and to respond to surge voltageinstantaneously.

i There have been known, on the other hand, voltagenonlinear resistorsof bulk type comprising a sintered body of zinc oxide-with additivescomprising bismuth oxide and antimony oxide and/or cobalt oxide, as seenin U. S. Pat. No. 3,663,458. These zinc oxide varistors of bulk type arecontrollable in a Cvalue by changing the distance between electrodes andhave an excellent nonlinear property with an n-value more than 10 in aregion of current below than IOA/cr'n. Fora current more than l0A/cmhowever, the n-value goes down to a value below than 10. The powerdissipation for surge energy shows a relatively low value compared.withthat of the conventional silicon carbide arrester,

so that the change rate of C-value exceeds 20percentattsttwo;srandarqlishms sssrsss of 4 331 Wave formin a peak current ofl,50 0A]cm are applied to said zinc oxide varistor of the bulk type.There is known'anotherzinc oxide varistor of bulk type which contains asan additive nickel fluoride as seen in U. S. Pat. No. 3,687,871. Thisvaristor shows an excellent nonlinear property, but an essentially weakpoint as an arrester element is its weakness with respect to surgepulses. The nonlinear property of the varistor deteriorates easily evenfor IOOA/cm of surge pulse.

An object of the present invention is to provide a voltage-nonlinearresistor having nonlinearity due to the bulk thereof and beingcharacterized by a-high nvalue even in a range of current more thanlOA/cm.

Another object of the present invention is toprovide a voltage-nonlinearresistor having high power dissipation for surge energy.

. Another object of the present invention is to provide an arrestercharacterized by high suppression for lightning surges and lowfollowcurrent.

These and other objects of the invention will become apparent uponconsideration of the following description taken together with theaccompanying drawing in which FIG. 1 is a partial cross-sectional viewthrough a voltage-nonlinear resistor in accordance with the inventionand FIG. 2 and FIG. 3 partial cross-sectional views through an arresterin accordance with the invention.

Before proceeding with a detailed description of the voltage-nonlinearresistorscontemplated by the invention, their construction will bedescribed with reference to FIG. 1 wherein reference character 10designates, as a whole, a voltage-nonlinear resistor compri sing,'as itsactive element, a sintered body having a pair of electrodes and 3applied to opposite surfaces thereof.

, Said sintered body 1 is prepared in a manner hereinaf-v ter set forth.Wireleads Sand 6 are attached conductively to the electrodes 2 and 3,respectively, by a connection means 4 such as solder or the like. 7

A voltage-nonlinear resistor according to the invention comprises asintered body of a composition comprising, as an additive, 0.1 to 3.0mole percent of bismuth oxide (Bi O 0.05 to 3.0 mole percent of antimonyoxide Sb-,; O and 0.1 to 3.0 mole percent of nickel fluoride (NiFQ), andthe remainder of zinc oxide (ZnO) as a main constituent, and electrodesapplied to opposite surfaces of said sintered body. Such avoltagenonlinear resistor has non-ohmic resistance due to the bulkitself. Therefore, its C-value can be changed without impairing then-value by changing the distance be- 1 The higher n-value in a region ofcurrent more than IOA/cm can be obtained when said sintered body furtherincludes one member selected from the group consisting of 0.1 to 3.0mole percent of cobalt oxide (C) and 0.1 to 3.0 'mole percent ofmanganese oxide According to the present invention, the higher nvalue ina region of current more than IOA/cm and the higher stability for surgepulses can be obtained when said sintered body comprises, as a mainconstituent, Zinc oxide (ZnO) and, as an additive, 0.1 to 3.0 molepercent of bismuth oxide (Bi O 0.05 to 3.0 mole percent of antimonyoxide (Sb O 0.1 to 3.0 mole percent of nickel fluoride (MP 0.] to 3.0mole percent of cobalt oxide (C00), 0.] to 3.0 mole percent of manganeseoxide (MnO) and one member selected from the group consisting of 0.05 to3.0 mole percent of chromium oxide (Cr O 0.1 to 3.0 mole percent oftinoxide (SnO' and 0.1 to 10.0 mole percent of silicon dioxide (SiOAccording to the present invention, the resistor is remarkably improvedin the n-value in a region of current more than IOA/cm and the stabilityfor surge pulse when said sintered body consists essentially of 99.4 to72 mole percent of zinc oxide (ZnO) and, as an additive, 0.1 to 3.0 molepercent of bismuth oxide (Bi O 0.05 to 3.0 mole percent of antimonyoxide (Sb O 0.1 to 3.0 mole percent of nickel fluoride (NiF- 0.1 to 3.0mole percent of cobalt oxide (CoO), 0.1 to 3.0 mole percent of manganeseoxide (MnO), 0.05 to 3.0 mole percent of chromium oxide (Cr O and 0.1 to10.0 mole percent of silicon dioxide (SiO According to the presentinvention, when at least one voltage-nonlinear resistor consistingessentially ofa sintered body of a composition comprising as a mainconstituent, zinc oxide and, as an additive, 0.1 to 3.0 mole percent ofbismuth oxide Eno 0.05 to 3.0 mole percent of antimony oxide (Sb O and0.1 to 3.0 mole percent of nickel fluoride (NiF and electrodes appliedto opposite surfaces of said sintered body, is applied to an arrester asa characteristic element, the resultant arrester is lowered in thefollow current and improved in the suppression and power dissipation forlightning surges.

According to the present invention, when at least one voltage-nonlinearresistor consisting essentially of a sintered body of 99.4 to 72.0 molepercent of zinc oxide (ZnO), 0.1 to 3.0 mole I percent of bismuth oxide(Bi O 0.05 to 3.0 mole percent of antimony oxide (Sb O 0.-l to 3.0 molepercent of nickel fluoride (NiF 0.1 to 3.0 mole percent of cobalt oxide(C00),

0.1 to 3.0 mole percent of manganese oxide (MnO),

0.05 to 3.0 mole percent of chromium oxide (Cr O and 0.1 to l0.0,molepercent of silicon dioxide (SiO and electrodes applied to oppositesurfaces of said sintered body, is applied as a characteristic elementto an arrester, the resultant arrester is further lowered in the followcurrent and is further improved in the suppression and power dissipationfor lightning surge.

The sintered body 1 can be prepared by a per se well known ceramictechnique. The starting materials in the compositions in the foregoingdescription are mixed in a wet mill so as to produce homogeneousmixtures. The

mixtures are dried and pressed in a mold into desired shapes at apressure from 50 l(g./cm to 500 Kg./cm The pressed bodies are sinteredin air at I,000 to 1,450C for l to 10 hours, and then furnacecooled toroom temperature (about 15C to about 30C). The mixtures can bepreliminarily calcined at 700 to 1,000C and pulverized for easyfabrication in the subsequent pressing step. The mixture to be pressedcan be admixed with a suitable binder such as water, polyvinyl alcohol,etc. It is advantageous that the sintered body be lapped at the oppositesurfaces by abrasive powder such as silicon carbide in a particle sizeof 50a in mean diameter to 10].. in mean diameter. The sintered bodiesare provided, at the opposite surfaces thereof, with electrodes by anyavailable and suitable method, such as silver painting, vacuumevaporation or flame spraying of a metal such as Al, Zn, Sn, etc.

The voltage-nonlinear properties are not practically affected by thekinds of electrodes used, but are affected by the thickness of thesintered bodies. Particularly, the C-value varies in proportion to thethickness of the sintered bodies, while the n-value is almostindependent of the thickness. This surely means that thevoltage-nonlinear property is due to the bulk itself, but not to theelectrodes.

Lead wires can be attached to the electrodes in a per se conventionalmanner by using conventional solder. It is convenient to employ aconductive adhesive comprising silver powder and resin in an organicsolvent in order to connect the lead wires to the electrodes.Voltage-nonlinear resistors according to this invention have a highstability to temperature and for the surge test, which is carried out byapplying lightning surge determined by the .IEC (JapaneseElectrotechnical Committee)-l56 Standard. The n-value and-C-value do notchange remarkably after heating cycles and surge test. It isadvantageous for achievement of a high stability to humidity and highsurge that the resultant voltagenonlinear resistors are embedded in ahumidity proof resin such as epoxy resin and phenol resin in a per sewell known manner.

When voltage-nonlinear resistors according to this invention are used asa characteristic element, the resultant arrester is improved remarkablyin the follow current and the suppression property for lightning surge.FIG. 2 is the cross-sectional view of an arrester wherein referencecharacter 20 designates, as a whole, an arrester comprising one or morevoltage-nonlinear resistors 11 ac'cordingto this invention as acharacteristic element are connected in series with one or moredischarging gaps'12, spring 13 and line terminals 14 and 15. Saidarrester elements are enveloped into wetprocess porcelain 16. Saidarrester is kept to a level below 'luA in follow current and to a levelhigher than 2,000A/cm in the surge dissipation. FIG. 3 is thecrosssectional view of another arrester wherein reference character 30designates, as a whole, an arrester comprising at least onevoltage-nonlinear resistor according to this invention. In theembodiment shown FIG. 3, reference characters identical to those of FIG.2 have been employed to designate like elements. The arrester of FIG. 3is characterized, in its construction, to be without discharging gapand, in its electrical properties as having a response time shorter than0.1ps for high surges having very sharp rise, in addition to itsexcellent properties in follow current and surge dissipation. Presentlypreferred illustrative embodiments of the inven- EXAMPLE 2 tion are asfollows. l Zmc oxide incorporated with bismuth oxide, antimony oxide,andnickel fluoride in the c T able 2 is fabricated into the volta torsby the same process as that thickness is 20mm. The resulting. electricalare shown in Table 2, in which the values of m and n, are then-values'defined between 0. lmA and l between 100 and 1,000A,respectively. The im test is carried out by applying two im l0,000A. Itcan be easily understood addition of bismuth oxide, antimony oxide, andnickel fluoride as additives show the high n-value and small changerates.

5 m m m m 1 w u i 1 mauh u PiP 2 0 r. mm 5" i m C a w EXAMPLE 1 Astarting material composed of 98.0 mole of zinc oxide, 0.5 mole-percentof bismuth ox mole percent of antimony oxide of nickel fluoride is mixedin a The mixture is dried and pressed in a mold into discs of 40mm indiameter and 25mm in thickness at a pressure of 250Kg/cm I I v Changerates in after test (percent) 100- 1,000 a. AC A121 A714 TABLE 2Electrical properties of resultant resistor Additives (mol. m

percent) 0 (atl 0.1-1 51,20 NiFz ma.) ma.

BizOa The pressed bodies are sintered in air at the condition shown inTable l, and then furnace-cooled to room temperature.- The sintered bodyis lapped at the opposite surfaces thereof into the thickness shown inTable l by silicon carbide abrasive in particle size of 30p, in meansdiameter- The opposite surfaces of the sintered body are provided with aspray metallized film ofaluminum in a per se well known technique.

The electric characteristics the resultant sintered body are shown inTable l, which shows the C-value varies approximately in proportion tothe thickness of the sintered body while the n-value isessentiallyindependent of the thickness. It will be readily realizedthat the voltage-nonlinear property of the sintered body is 25attributed to the sintered body itself.

EXAMPLE 3 Zinc oxide and additives of Table 3 are fabricated into thevoltage-nonlinear resistors by the same process as that of Example 1.The electrical properties of the resulting resistors. are shown in Table3 The change TABLE 1 rates of C and n values after the impulse test arecarried out by same method as that of Example 2- are also shown in Table3. It will be readily realized that the further addition of cobalt oxideor manganese oxide results in a higher n-value and smaller change ratesthan 2 e l. m a X E f o e s 0 h t. 0 a dv mm mm r .1. m annmHHHHmmmmHHHw -D555 1 t t 0001 t 111 n n v t ,CCCC I v i Q WW O OCCCTC0000 a t 00003 0 0W 222211110m0 lill 0.00] A n m334344546667 0 A m 10500 000 ph -0200590002 0 5 5840370500 73 732 5 s mMiO N50 N50 (l\ 5( 5( 5i t t t .m .m m .m

Change rates after test (percent) 1,000 a. AC Am TABLE 3 Electricalproperties of Additives (moi. percent) resultant resistor t 1 0.1-1ShzOa NiFz C00 MnO 1 ms.) ma.

wmeemamwmwmmmeam an mmmm mmwmmmm 7 11111111 11 11111 0.111000111000105 30 0 0 on&0 0 0 a33 0 &0

1 1101101100100100511011011000001005 0 0 3 0 03 0 0 &3 0& 3 0 Qw&000&00300331330330 555055050500500002055055050 00050000 0 .00 .0 .0 n w imabamaamaaarn EXAMPLE 4 EXAMPLE 5 The voltage-nonlinear resistorsaccording to Example 2, 3 and 4 are employed in the arresterconstruction s shgwn 01.5 B bust sysansskn of 3 pieces of resistor and ldischarging gap. The C-value oFsaid total pieces of voltage-nonlinearresistor is about 7,000V. The impulse tests are carried out by applyingtwo impulses -of 4 10p.s, 1,500A/cm superposed on AC 3000V. The followcurrent of the arrester shows a value lower than 1 4A as shown in Table6 and the change rates of electrical properties after the test show sameresults asthe impulse test of Example 2, 3 and 4.

TABLE 4 Electrical properties of Change rates after test Additives (moi.percent) resultant resistor (percent) C 0.1-1 100- SD20: NiFz C M110SnOz CnO; 810; (at 1 ma.) ma. 1,000 a. AC Am Am 0. 0. 1 0. 1 0.1 0. 1 1,920 35 13 -10 -10 -5.1 0.05 0.1 0.1 0.1 0.5 2,000 37 19 -10 -33 -35 0.050.1 0.1 0.1 3.0 2,250 37 10 -11 -3.1 -00 1.0 0.5 0.5 0.5 0.1 2,300 37 18-11 -32 -3.5 1.0 0.5 0.5 0.5 0.5 2,500 40 23 -3.0 -51 -24 1.0 0.5 0.50.5 3.0 2,540 37 10 -02 -7.4 -5.1 3.0 3.0 3.0 3.0 0.1 3,100 35 19 -10-32 -52 3.0 3.0 3.0 3.0 0.5 3,250 35 1s -19.7 -33 -39 3.0 3.0 3.0 3.03.0 3,550 34 18 -04 -9.0 -53 0.05 0.1 0.1 0.1 .05 2,200 33 13 -10 -37-5.5 0.05 0.1 0.1 0.1 .5 2,300 33 19 -03 -34 -4.0 0.05 0.1 0,1 0.1 .02,520 40 -11 -7.5 .-4.2 1.0 0.5 0.5 0.5 .05 2,500 42 10 -5.0 -3.7 1.00.5 0.5 0.5 0.5 3,000 45 23 -7.0 -5.2 -23 1.0 0.5 0.5 0.5 3.0 3,150 19-10 -7.0 -3.7 3.0 3.0 3.0 3.0 0. 05 3,300 42 20 -9.2 -7.5 -43 3.0 3.03.0 3.0 0.5 4,050 41 20 -10 -07 -50 3. 0 3. 0 3. 0 3. 0 3. 0 4, 320 3313 -10 -s. s -5. a 0. 05- 0.1 0.1 0.1 0.1 2, 250 33 19 0. 3 -11. 0 -11.2 0.05 0.1 0.1 0.1 0.5 2,500 40 20 0.0 3.7 -53 0.05 0.1 0.1 0.1 10.04,500 41 20 -s.3 -31 -5.o 1. 0 0. 5 0. 5 0. 5 0.1 2, 550 43 21 -12. 7-7. 3 -4. 4 1.0 0.5 0.5 0.5 0.5 3,300 43 23 -7.0 -5.2 -23 1.0 0.5 0.50.5 10.0 5,300 43 21 -02 -7.7 -5.4 3.0 3.0 3.0 3.0 0.1 3,500 39 20 -00-7.0 -5.2 3.0 3.0 3.0 3.0 0.5 4,250 41 20 -32 -7.s -4.7 3.0 3.0 3.0 3.010.0 7,000 30 10 -33 -35 -5. 1 0.05 0.1 0.1 0.1 .05 0.1 2,750 42 20 -37-57 -30 0.05 0.1 0.1 0.1 .05 0.5 3,000 43 21 -7.7 -5.7 -2.7 0.05 0.1 0.10.1 .05 10.0 5,400 43 21 -s.0 -7.0 -4. 1 1.0 0.5 0.5 0.5 0.5 0.1 3,20043 22 -7.3 -52 -45 1.0 0.5 0.5 0.5 0.5 0.5 4,000 25 -50 -4.7 -2.2 1.00.5 0.5 0.5 0.5 10.0 7,500 47 21 -7.4 -5.0 -4.1 3.0 3.0 3.0 3.0 3.0 0.14,200 41 22 83 -33 3.0 3.0 3.0 3.0 3.0 0.5 5,200 43 21 -7.2 -s.2 -32 3.03.0 3.0 3.0 3.0 10.0 5,300 41 20 -35- -7.5 -4.4

EXAMPLE 5 TABLE 6 45 The resistorsof Example 2, 3 and 4 are tested inac- Sample No. Follow-current cordance with a method widely used forelectronic Example 2 v below "um um components parts. The heating cycletest is carried out Example 3 below than 0.5 /4 by repeating 5 times thecycle in WhlCh said reslstors Example-4 balm" than O-ULA are kept at Cambient temperature for 30 minutes, 50

cooled rapidly to 20C and then kept at such temperature for 30 minutes.The humidity 'test is carried out at 40C and percent relativehumidityfor 1,000 hrs. Table 5 shows the average change rates of C-value andn-value .of resistors after heating cycle test and humidity test. It iseasily understood that each sample has a small change rate. 4

TABLE 5 EXAMPLE 7 The voltage-nonlinear resistors according to Example2, 3 and 4 are employed in the arrester construction ample 6. The followcurrent shows a value lower than l/IAEEEHGWn in Table Find the changerates ofelectrical properties after testing show same the results as ithat of. the impulse test in Example 2, 3 and 4. Another ing the valueof 0.-l;zs in-rise time. The risetime of 7 current flowing through saidarrester is lower than 0.05us.

What is claimed is:

l. A voltage-nonlinear resistor consisting essentially of a sinteredbody of a composition comprising as a main constituent, zinc oxide (ZnO)and, as an additive, 0.! to 3.0 mole percent of bismuth oxide (850;),0.05 to 30 mole percentof antimony oxide (Sb O and 0.1 to 3.0 molepercent of nickel fluoride (MB), and electrodes applied to oppositesurfaces of said sintered body.

2. A voltage-nonlinear resistor defined by claim 1, wherein saidsintered body further includes one member selected from the groupconsisting of 0.1 to 3.0 mole percent of cobalt oxide (C00) and 0.1 to3.0 mole percent of manganese oxide (MnO).

3. A voltage-nonlinear resistor defined by claim 1, wherein saidsintered body further includes 0.1 to 3.0 mole percent of cobalt oxide(CoO), 0.1 to 3.0 mole percent of manganese oxide (M'nO) and one memberselected from the group to 3.0 mole percent of chromium oxide (C150 01to 3.0 mole percent of tin oxide (SnO and 0.1 to 10.0 mole percent ofsilicon dioxide (SiO 4. A voltage-nonlinear resistor defined by claim 1,wherein said sintered body consisting essentially of 99.4 to 72.0 molepercent of zinc oxide (ZnO) 0.1 to

3.0 mole percent of bismuth oxide (Bi O 0.05 to 3.0

mole percent of antimony 0xidev(Sb O; 0.1 to 3.0 mole percent of nickelfluoride (MB), 0.1 to 3.0 mole percent of cobalt oxide C00), 0.1 to 3.0mole percent of manganese oxide (MnO), 0.05 to 3.0 mole percent ment.

2. A voltage-nonlinear resistor defined by claim 1, wherein saidsintered body further includes one member selected from the groupconsisting of 0.1 to 3.0 mole percent of cobalt oxide (CoO) and 0.1 to3.0 mole percent of manganese oxide (MnO).
 3. A voltage-nonlinearresistor defined by claim 1, wherein said sintered body further includes0.1 to 3.0 mole percent of cobalt oxide (CoO), 0.1 to 3.0 mole percentof manganese oxide (MnO) and one member selected from the groupconsisting of 0.05 to 3.0 mole percent of chromium oxide (Cr2O3), 0.1 to3.0 mole percent of tin oxide (SnO2) and 0.1 to 10.0 mole percent ofsilicon dioxide (SiO2).
 4. A voltage-nonlinear resistor defined by claim1, wherein said sintered body consisting essentially of 99.4 to 72.0mole percent of zinc oxide (ZnO) 0.1 to 3.0 mole percent of bismuthoxide (Bi2O3), 0.05 to 3.0 mole percent of antimony oxide (Sb2O3), 0.1to 3.0 mole percent of nickel fluoride (NiF2), 0.1 to 3.0 mole percentof cobalt oxide (CoO), 0.1 to 3.0 mole percent of manganese oxide (MnO),0.05 to 3.0 mole percent of chromium oxide (Cr2O3) and 0.1 to 10.0 molepercent of silicon dioxide (SiO2).
 5. An arrester comprising at leastone voltage-nonlinear resistor of claim 1 as a characteristic element.6. An arrester comprising at least one voltage-nonlinear resistor ofclaim 4 as a characteristic element.